Susanne Höhne

Adsorption of Poly(vinylformamide-co-vinylamine) Polymers (PVFA-co-PVAm) on Copper

The adsorption of poly(vinylformamide) (PVFA) and its derivative statistical copolymer poly(vinyl-formamide-co-vinylamine) (PVFA-co-PVAm) on metallic copper and copper oxide particles as well as planar copper surfaces was studied as a function of the degree of hydrolysis of PVFA, the pH, and the polymer concentration in solution. The chemical composition and molecular structure of the PVFA-co-PVAm layers were investigated by surface-sensitive spectroscopic methods such as XPS, DRIFT spectroscopy, and ellipsometry. The findings allowed us to explain the adsorption mechanisms and the forces driving the PVFA-co-PVAm adsorption. It was shown that PVFA-co-PVAm layers thicker than 30 nm are able to protect the planar copper surface against corrosive attack.

The cationic polymerization of 2‐vinylfuran on the surface of silica particles – an NMR spectroscopic study

The cationic polymerization of 2-vinylfuran initiated with triphenylmethyl chloride in conjunction with silica nanoparticles in suspension yields poly(2-vinylfuran)/silica hybrid particles and a soluble fraction of oligo(2-vinylfuran). 2-Vinylfuran cationically is polymerized via both the vinyl double bond and the 5-position of the furan ring. The formation of the resulting crosslinked poly(2-vinylfuran) network structure on the surface of the silica particles is examined by means of different kinds of NMR spectroscopy and an assignment of the signals is given.

Hydrophobically Functionalized Chitosan Particles

Particles of chitosan have a very polar surface, and thus they are easily wetted by water and also dissolve in acidic media. The hydroxyl and amino groups offer a high potential for grafting reactions. Aldehydes and carbonic acid derivatives were covalently grafted, preferably onto the amino groups. The reactions were carried out in solution as homogeneous phase reactions as well as on the particle surfaces as heterogeneous phase reactions. Covalently bonded alkyl chains impart the chitosan molecules with hydrophobic properties. We employed different methods such as NMR, XPS, elemental analysis and FT-IR spectroscopy to study the reactions and to estimate the degree of functionalization. The wetting behavior of the particles was investigated by a modified Wilhelmy technique, where an adhesive tape completely coated with the particles was dipped in water. Some of the samples having a high degree of functionalization showed super-hydrophobic surface properties. The observed super-hydrophobic effect results from a combination of the hydrophobic properties of the modified particles and the roughness of the particle coating.